On Mon, 04 May 2009 13:14:04 +0200, noname wrote:

Now, where (if any) should I add grounding to that setup? I was going
to add a lightning arrester to the coax just before it enters the
house (fed into two ground rods), but will forego that since none seem
overly thrilled about the idea.

Hi Stewart,

A very good description of your set-up. You are already grounded
through a the haphazard path of your AC outlet - if you chose to use
three prong connections, if your outlet is in fact grounded, if your
equipment actually has a safety ground to chassis. A lot of "ifs,"
hence my use of "haphazard."

By deliberately adding a ground wire going to an ad-hoc ground rod,
you can easily introduce problems. The worst of which could be
lethal, but that extreme is unlikely (except it might only be resolved
at the coroner's inquest).

Consult code for grounding requirements.

The minor problems include ground loops that can plague your listening
and/or your contacts asking what that strange music is in the
background of your transmission. The loops can burn out wiring in
your rig (actually, more like traces on cards). The oddities that
arise from ad-hoc grounding scroll out on a list of complaints that
many come here to find solution for.

By the way, a Yeasu technician once recommended salting ground rods to
resolve a poor grounding situation at the time, so I've been doing
that ever since (can't hurt), especially during the dry summer months.
Adding water is pretty obvious, so didn't think I needed to spell that
out, Dave.

That sounds like a fantasy. If this thread doesn't grow suitably to
fill in the vacuum of information, you can do a search in google
groups, for this group, using the key word GROUND and CODE.

73's
Richard Clark, KB7QHC

In article ,
Richard Clark wrote:

By the way, a Yeasu technician once recommended salting ground rods to
resolve a poor grounding situation at the time, so I've been doing
that ever since (can't hurt), especially during the dry summer months.
Adding water is pretty obvious, so didn't think I needed to spell that
out, Dave.

That sounds like a fantasy. If this thread doesn't grow suitably to
fill in the vacuum of information, you can do a search in google
groups, for this group, using the key word GROUND and CODE.

73's
Richard Clark, KB7QHC

It really depends on the area that your trying to build the RF Ground
on, or into. Here in Alaska much of the earth (Dirt) is just plain
Silica Sand, and rock, with very little mineralite in it, and is about
as effective an RF Ground as a piece of Glass. We use Dipoles a lot just
for that reason as they don't required an RF Ground to work against to
radiate effectively. In some areas where Marconi type Antennas are used,
and one MUST have an effective RF Ground, we have used Chicken Wire
panels laid flat out from the base to 1/4 Wave at the lowest Frequency
of intended use, and then Salted the dirt to add to the effective
conductance of the Ground plane untill the chicken wire Rusts to the
point of leaving just the conductive material in the top of the dirt.
The Commercial AutoTune Antenna Tuners really don't work well without an
effective RF Ground to work against, as the Microcode that runs them,
can't deal with the very non-stable RF Grounding Systems. There are a
number of ways to get single-ended Autotuners to tune Balanced Dipole
type Antennas, and those are used as well. Much of the work done in the
commercial MF/HF Communications Antennas Systems here in Alaska, was
pioneered by the Engineering Staffs of the old Northern Radio Company,
and then continued by Stephens Engineering Associates. (SEA) Both
outfits were leaders in Bush Communications here in Alaska, in their day.

--
Bruce in alaska
add path after fast to reply

On Mon, 04 May 2009, Richard Clark wrote:

A very good description of your set-up. You are already
grounded through a the haphazard path of your AC outlet
- if you chose to use three prong connections, if your outlet
is in fact grounded, if your equipment actually has a safety
ground to chassis. A lot of "ifs," hence my use of "haphazard."


Okay, I have checked each of those. The house was recently inspected
ensure compliance with recent building code requirements, with the
outlets and overall grounding system checked for proper wiring at that
time. The house wiring exceeded current building requirements, which I
was indeed happy to hear.

The radio uses a three-prong cord (a requirement here), with the
chassis apparently connected at several points to the ground of that.
It appears the antenna shield side of the connector is also bolted
directly to that chassis.


By deliberately adding a ground wire going to an ad-hoc
ground rod, you can easily introduce problems. (snip)


So you recommend no additional grounding?

stewart / w5net

On Tue, 05 May 2009 17:10:16 +0200, noname wrote:

On Mon, 04 May 2009, Richard Clark wrote:

A very good description of your set-up. You are already
grounded through a the haphazard path of your AC outlet
- if you chose to use three prong connections, if your outlet
is in fact grounded, if your equipment actually has a safety
ground to chassis. A lot of "ifs," hence my use of "haphazard."


Okay, I have checked each of those. The house was recently inspected
ensure compliance with recent building code requirements, with the
outlets and overall grounding system checked for proper wiring at that
time. The house wiring exceeded current building requirements, which I
was indeed happy to hear.

Hi Steve,

So, in fact your three prong plugs find their way to the panel ground.
Can YOU find that ground?


The radio uses a three-prong cord (a requirement here), with the
chassis apparently connected at several points to the ground of that.
It appears the antenna shield side of the connector is also bolted
directly to that chassis.

So, by this explicit statement, your "balanced" antenna has been
unbalanced at the rig (which only further enforces the unbalance by
virtue of the coax connection).

By deliberately adding a ground wire going to an ad-hoc
ground rod, you can easily introduce problems. (snip)


So you recommend no additional grounding?

This is a loaded question because there are TWO grounds which
discussion often gets mixed. They may both go to the same point of
zero potential, but their paths are what distinguish them. The TWO
grounds are safety ground and RF ground. Any wire that is
significantly long at a wavelength of your operation, will qualify
more as a radiator than it will as a ground wire.

Consider you are sitting at your transmitter, it has a dedicated newly
applied ground wire that runs the shortest distance to what you think
of as ground. Maybe that is all of 10 feet. You are operating on
10M. Ground is a quarterwave away. That puts your equipment at the
high potential end of a wire with zero potential at ground. How
grounded does that sound?

The solution there is to add an artificial ground tuner to move that
potential away from you (this would be an attempt to "balance" the
distribution so that your equipment sits at an artificially imposed
neutral - ground of another mother).

Thing is, as I said, you already have a ground connection. The safety
ground is a necessity unless you are very practiced in the art of
isolation. You can add another path, and, again, that path may be a
different length to the one you already have. Given that situation,
you may find one path now spilling current into the new one - as
dependant upon the wavelength of operation and the physical path
lengths. When this spilling from one path into the other occurs,
strange things happen compared to if you hadn't added that new path.

More's to be said, but that's enough for now.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Tue, 05 May 2009 17:10:16 +0200, noname wrote:

On Mon, 04 May 2009, Richard Clark wrote:
A very good description of your set-up. You are already
grounded through a the haphazard path of your AC outlet
- if you chose to use three prong connections, if your outlet
is in fact grounded, if your equipment actually has a safety
ground to chassis. A lot of "ifs," hence my use of "haphazard."

Okay, I have checked each of those. The house was recently inspected
ensure compliance with recent building code requirements, with the
outlets and overall grounding system checked for proper wiring at that
time. The house wiring exceeded current building requirements, which I
was indeed happy to hear.

Hi Steve,

So, in fact your three prong plugs find their way to the panel ground.
Can YOU find that ground?

The radio uses a three-prong cord (a requirement here), with the
chassis apparently connected at several points to the ground of that.
It appears the antenna shield side of the connector is also bolted
directly to that chassis.

So, by this explicit statement, your "balanced" antenna has been
unbalanced at the rig (which only further enforces the unbalance by
virtue of the coax connection).

By deliberately adding a ground wire going to an ad-hoc
ground rod, you can easily introduce problems. (snip)

So you recommend no additional grounding?

This is a loaded question because there are TWO grounds which
discussion often gets mixed. They may both go to the same point of
zero potential, but their paths are what distinguish them. The TWO
grounds are safety ground and RF ground. Any wire that is
significantly long at a wavelength of your operation, will qualify
more as a radiator than it will as a ground wire.

Consider you are sitting at your transmitter, it has a dedicated newly
applied ground wire that runs the shortest distance to what you think
of as ground. Maybe that is all of 10 feet. You are operating on
10M. Ground is a quarterwave away. That puts your equipment at the
high potential end of a wire with zero potential at ground. How
grounded does that sound?

Worse than that. You've basically made a big loop antenna: greenwire
ground to panel, panel to ground rod, ground rod to rig.





The solution there is to add an artificial ground tuner to move that
potential away from you (this would be an attempt to "balance" the
distribution so that your equipment sits at an artificially imposed
neutral - ground of another mother).

Or, easier.. put a choke around the feedline where it comes into the
shack, so that there's no appreciable RF current through the chassis and
green-wire ground.




Thing is, as I said, you already have a ground connection. The safety
ground is a necessity unless you are very practiced in the art of
isolation. You can add another path, and, again, that path may be a
different length to the one you already have. Given that situation,
you may find one path now spilling current into the new one - as
dependant upon the wavelength of operation and the physical path
lengths. When this spilling from one path into the other occurs,
strange things happen compared to if you hadn't added that new path.


Exactly.. one DC/Line frequency path is all that's needed for safety.

Jim Lux wrote:

Or, easier.. put a choke around the feedline where it comes
into the shack, so that there's no appreciable RF current
through the chassis and green-wire ground.


Okay, I'm adding a balun. Now the question is what and where. The
assembly instructions for the antenna say...

The antenna is "..designed to be used with
50 ohm coax cable. No balun is required for
proper operation.

If RF on the coax is a problem, simply wind
a "choke balun" with the coax that's used for
your feedline. Wind approx 8 turns, at about
an 8 inch diameter and tape (with outdoor rated
black electrical tape), like a donut, and place
this "donut" near the feedpoint of the antenna.
You should leave about 2 foot of your coax
sticking out of this "donut" for connection to
the antenna. Then attach the end of your
coax to the antenna connector on the center
insulator, with the coax connector that is
already on your feed line."

In other words, a scramble-winding choke near the antenna's feedpoint.
The alternative is an MFJ-915 in-line balun with 50 ferrite core beads
on coax (cheaper than I can buy the ferrites), which MFJ says should
be installed closer to the radio (3 feet) as opposed to the antenna
feedpoint at the other end of the coax as described above.

Which of the two options is most sufficient for the task and which is
the correct placement for this - or are they both right depending on
the type?

stewart / w5net

On Wed, 06 May 2009 01:54:34 +0200, noname wrote:

Okay, I'm adding a balun. Now the question is what and where. The
assembly instructions for the antenna say...

Hi Stewart,

The answer to that is driven by the perceived problem. In a nutshell,
if you don't have a problem, you don't need the balun (or choke).

Knowing that you have a problem is another matter; but if you don't
know what the problem is (the perception), you wouldn't know if it got
fixed either.

73's
Richard Clark, KB7QHC

Richard Clark wrote:

Hi Stewart,

The answer to that is driven by the perceived problem. In a
nutshell, if you don't have a problem, you don't need the
balun (or choke).

Knowing that you have a problem is another matter; but if
you don't know what the problem is (the perception), you
wouldn't know if it got fixed either.


Wow, your messages get more cryptic as they go along. I thought the
very first message made it clear I'm not trying to fix a specific
problem, but instead trying to head off some of the more common
problems associated with a setup like this.

Again, this is an entirely a new setup which has not been installed
yet. What I'm seeking here is some input on the best way to do that.
I'm fairly familiar with the basics of dipole antennas, but hoping for
some solid advice from those with a lot more experience than my own.

stewart / w5net

noname wrote:
Jim Lux wrote:
Or, easier.. put a choke around the feedline where it comes
into the shack, so that there's no appreciable RF current
through the chassis and green-wire ground.


Okay, I'm adding a balun. Now the question is what and where. The
assembly instructions for the antenna say...

The antenna is "..designed to be used with
50 ohm coax cable. No balun is required for
proper operation.

If RF on the coax is a problem, simply wind
a "choke balun" with the coax that's used for
your feedline. Wind approx 8 turns, at about
an 8 inch diameter and tape (with outdoor rated
black electrical tape), like a donut, and place
this "donut" near the feedpoint of the antenna.
You should leave about 2 foot of your coax
sticking out of this "donut" for connection to
the antenna. Then attach the end of your
coax to the antenna connector on the center
insulator, with the coax connector that is
already on your feed line."

In other words, a scramble-winding choke near the antenna's feedpoint.
The alternative is an MFJ-915 in-line balun with 50 ferrite core beads
on coax (cheaper than I can buy the ferrites), which MFJ says should
be installed closer to the radio (3 feet) as opposed to the antenna
feedpoint at the other end of the coax as described above.

Which of the two options is most sufficient for the task and which is
the correct placement for this - or are they both right depending on
the type?



Read Jim Brown's RFI-Ham.pdf referenced in an earlier post.

"choke baluns" made by winding coax are pretty much single band devices.

A better approach is a single 2.4" toroid of suitable mix (#31 is good),
and put a dozen turns of your RG-8x on it. Put one at the feedpoint,
put one where it comes in the shack. Buy some extra cores because they
make good RF filters for things like power cords (and the hole is big
enough that a standard IEC power connector will fit through them)

The MFJ915 is fine, although I wasn't able to find any actual
performance specifications or details of what mix they're using. (in a
few minutes of casual googling).. MFJs is probably an incarnation of the
"W2DU balun", so the data Jim measured is probably reasonable. (about
1500ohms peaking at 10MHz)

I think you'll get better results (cheaper) with the single big
toroid..5 turns gives you more impedance than the W2DU, and it goes up
from there ( based on the measurements in K9YCs paper.. page 12). The
toroids run about $5. Most of the gain is from using a better mix (31)

On May 5, 7:26*pm, Jim Lux wrote:
noname wrote:
Jim Lux wrote:
Or, easier.. put a choke around the feedline where it comes
into the shack, so that there's no appreciable RF current
through the chassis and green-wire ground.

Okay, I'm adding a balun. Now the question is what and where. The
assembly instructions for the antenna say...

* The antenna is "..designed to be used with
* 50 ohm coax cable. No balun is required for
* proper operation.

* If RF on the coax is a problem, simply wind
* a "choke balun" with the coax that's used for
* your feedline. Wind approx 8 turns, at about
* an 8 inch diameter and tape (with outdoor rated
* black electrical tape), like a donut, and place
* this "donut" near the feedpoint of the antenna.
* You should leave about 2 foot of your coax
* sticking out of this "donut" for connection to
* the antenna. Then attach the end of your
* coax to the antenna connector on the center
* insulator, with the coax connector that is
* already on your feed line."

In other words, a scramble-winding choke near the antenna's feedpoint.
The alternative is an MFJ-915 in-line balun with 50 ferrite core beads
on coax (cheaper than I can buy the ferrites), which MFJ says should
be installed closer to the radio (3 feet) as opposed to the antenna
feedpoint at the other end of the coax as described above.

Which of the two options is most sufficient for the task and which is
the correct placement for this - or are they both right depending on
the type?

Read Jim Brown's RFI-Ham.pdf referenced in an earlier post.

"choke baluns" made by winding coax are pretty much single band devices.

A better approach is a single 2.4" toroid of suitable mix (#31 is good),
and put a dozen turns of your RG-8x on it. * Put one at the feedpoint,
put one where it comes in the shack. *Buy some extra cores because they
make good RF filters for things like power cords (and the hole is big
enough that a standard IEC power connector will fit through them)

The MFJ915 is fine, although I wasn't able to find any actual
performance specifications or details of what mix they're using. (in a
few minutes of casual googling).. MFJs is probably an incarnation of the
"W2DU balun", so the data Jim measured is probably reasonable. (about
1500ohms peaking at 10MHz)

I think you'll get better results (cheaper) with the single big
toroid..5 turns gives you more impedance than the W2DU, and it goes up
from there ( based on the measurements in K9YCs paper.. page 12). The
toroids run about $5. *Most of the gain is from using a better mix (31)

What if you use a coax with two shields, one shield for chassis ground
which is the coax connection and the outer shield for earth/ground?
Yes, there could be a ground loop but the nearest ground to a strike/
antenna is probably the best protection